I had one fixed cup come loose on my Gitane. I hand tightened it several times on my way back to my starting point. Later I cleaned the threads with solvent and used Loctite on the threads. So far, so good.
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1971 Paramount P-13 Chrome
1973 Paramount P-15 Opaque Blue
1974 Raleigh Professional Blue Mink
1991 Waterford Paramount
Holland Titanium Dura Ace Group
Holland Titanium Ultegra Triple Group